Maintaining post-grazing sward height of Panicum maximum (cv. Mombaça) at 50ￂ cm led to higher animal performance compared with post-grazing height of 30ￂ cm

In swards of tall, tufted, tropical grasses like Mombaça guinea grass (Panicum maximum (Jacq.)), post-grazing heights promote changes in sward structure, which influence animal performance. This study evaluated changes in sward structure in response to grazing management at two post-grazing heights (30 and 50 cm), associated with 90 cm pre-grazing height. Each treatment was allocated to experimental unit (1.5 ha) in three replicated blocks. Pastures were evaluated pre- and post-grazing to estimate herbage mass, percentages of leaf (LP), stem (SP) and dead material (DP), and nutritive value (VN). Stocking rate was adjusted twice a week "using the put-and-take approach," and animals were weighed every 28 days. Forage accumulation rate was greater for pasture managed at 30 cm (64.8 vs. 55.1 kg ha-1 day-1) than 50 cm. A greater number of days were required after grazing 30-cm residual pasture to achieve the pre-grazing target height, resulting in 25% decrease in number of grazing cycles compared with pastures managed at 50 cm. Regardless of post-grazing height targets, SP and DP decreased, whereas LP and NV increased from soil level to top of canopy. Stocking rate was greater in pastures managed to 30 cm than in those managed to 50 cm residual height (4.7 vs. 3.4 AU ha-1). However, average daily gain was greater for 50 cm than for 30 cm post-grazing height (795 vs. 590 g steer-1 day-1), resulting in a greater animal production per area (917 vs. 794 kg/ha of live weight). Thus, Mombaça guinea grass subject to intermittent grazing should be managed at 50 cm residual height.